Malnutrition is a major cause of childhood mortality worldwide. Although we often tend to associate malnutrition with starvation, the two do not necessarily go hand in hand. In three recently published studies, researchers determined that certain gut bacteria are closely associated with malnourishment [1, 2, 3]. In one of these studies, Blanton et al. demonstrated that transplanting these bacteria from malnourished children into healthy mice caused those mice to exhibit symptoms of malnourishment despite eating the same diet as other healthy mice . This groundbreaking work has given us a better understanding of why diet alone may not be enough to solve certain difficult cases of malnutrition.
 Blanton, L. V. et al. Gut bacteria that prevent growth impairments transmitted by microbiota from malnourished children. Science 351, 10.1126/science.aad3311 (2016).
 Schwarzer, M. et al. Lactobacillus plantarum strain maintains growth of infant mice during chronic undernutrition. Science 351, 854-857 (2016).
 Charbonneau, M. R. et al. Sialylated Milk Oligosaccharides Promote Microbiota-Dependent Growth in Models of Infant Undernutrition. Cell 164, 859-871 (2016).